An Introduction to Git and Github

Some basics

Phil Lamond

Disclaimer: I'm not a Git guru

If you want to hear it from the horse's mouth, watch Git by a git (Linus Torvalds who also created and maintains the Linux kernel project)

Or read the git manual page/tutorial

Getting Going with Git

A vanilla project
```
git init
								
```

Inform git about who you are


git config --global user.name  "BBC Developer"
git config --global user.email bbc.developer@bbc.co.uk

And set up fancy colours in your terminal


git config --global color.ui true

Getting Going with Git

Get git to tell you what it thinks of your project
```
git status
								
```
Add the files you want under version control
```
git add file1 file2
								
```

Getting Going with Git

Commit your added files


git commit


git commit -m "My awesome code changes"

Or add and commit at the same time (catches all unversioned files)
```
git commit -a
								
```

Key Concepts

stage (commits)
origin (working copy)
attach to a remote
push to remote repo
pull from remote repo
branch which can be local and remote
master is remote head
merge a branch with one or more others...

Example

Imagine there are two developers working on the same project

Where am I at now?
```
git status
								
```
Better get changes from the remote master
```
git pull
								
```
(combines git fetch and git merge)

Example (continued)

Good, right those changes merged ok

Now commit and push my work


git status
git commit -a -m "These changes will get me kudos, man"
git push origin master

Example (continued)

That pushed up alright.
Ruh oh... those changes were not cool, I forgot to write unit tests and I've b0rkened the app!
Should've made a branch coz I wasn't finished!

Quick, rewind! Ok, make a branch first
```
git branch coolfeature
								
```
Rewind the remote master back by one changeset (push) and switch to the new branch (with my bad changes preserved)
```
git reset --hard HEAD^
git checkout coolfeature
								
```

Example (continued)

Push up the new branch

Now commit and push my work


git status
git commit -a -m "This will get me doughnuts and crisps, coz I now have unit tests"
git push origin coolfeature

Github

'Social coding'
Suits open source projects
Supports 'organisations'
Main remote git repository on the internet
Supports tickets (issues), documentation (pages), and notes/code snippets (gists)
Can 'fork' other projects at the click of a button

Github (continued)

Provides easy way to start a new project with git
Make a new Github repo with a README.md (description), then locally
```
git clone git://github.com/phillamond/mycoolrepo
								
```
Checks out and attaches your local working directory to the remote master

Github (continued)

Killer feature: pull requests

Creating a pull request creates an issue

Can be assigned to another user for code review and merging

Clean merges can be done on github.com

Really granular commenting (even on lines of code commits)

Powerful vetting system for code contributions

Demo

Conclusion

Caveat: I've only covered a core subset of git commands and github.com usage

Git is popular in the software development industry because of its really rich feature set that sets it apart from other (older) VCS systems like Subversion and CVS. It is used in earnest by big players like Google and Facebook and it seems a welcome move that the BBC are adopting it.